IT was the hottest summer for 80 years and Glasgow mum Ann Heron was determined to make the most of the good weather.

As temperatures soared to 40C on August 3, 1990, the former nurse decided to spend the afternoon sunbathing in her garden and listening to the radio.

Her home was Aeolian House, a large, detached property on the outskirts of Darlington, County Durham, where she had lived with her husband, Peter, 55, since marrying him four years earlier.

The pair had first met in 1980, on the Isle of Bute, Argyll, where she lived with her first husband police officer Ralph and three children.

They had moved from Kelvindale in Glasgow to the island to enjoy a more peaceful life.

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Peter, who was operations director for a successful haulage business in the north-east of England, had been on a golfing holiday to Scotland and was instantly taken with Ann.

Soon afterwards, both left their respective spouses and set up home together at Aeolian House.

Peter would go to work every day and Ann, originally from Drumchapel, had a part-time job in a local residential home.

The area they lived in was almost crime-free, safe. Everyone knew everyone and hardly anyone bothered to lock their doors.

That day in August 1990, it turned out to be a real scorcher. Peter went off to work as usual and Ann, then 44, remained at home.

She intended to make the best of the weather and do some sunbathing in their back garden.

Glasgow Times: The house where Ann was murderedThe house where Ann was murdered (Image: Newsquest)

Peter had come home around 1pm for a light lunch which they had shared together before heading back to an afternoon of business meetings.

However, a different sight would greet him when he returned to Aeolian House around 6pm.

He found his wife on the lounge floor, lying in a pool of blood with the radio still playing in the background.

Her bikini bottoms had been removed and her throat slashed.

Nothing had been stolen and there had been no signs of a break-in.

By the sun lounger lay a half-empty glass, her cigarettes, lighter and an ashtray. The Herons' pet collie Heidi snoozed peacefully nearby.

A horrified Peter called the police and soon the house became a murder scene.

Whoever killed her is believed to have been at the house an hour or so before Peter arrived home.

Witnesses later described seeing a man, with a deeply suntanned complexion and in his 30s, driving a blue Ford-type saloon car away from the property at high speed around 5pm.

In the weeks that followed the murder, it was a grieving Peter who found himself increasingly under suspicion and was the police’s number one suspect.

Glasgow Times: Police investigate Ann Heron's murderPolice investigate Ann Heron's murder (Image: Newsquest)

As they searched for motives, officers discovered the widower had recently started having an affair with a local barmaid.

There was also no sign of a break-in at Aeolian House, and police quickly ruled out a sexual motive for the brutal killing.

No murder weapon was found at the scene and with few witnesses or forensics the investigation into Ann’s murder stalled.

In 1994 a mystery man sent letters to a local paper, the police and Peter claiming to be the killer.

However, he was never traced or identified.

Peter was arrested in 2005 and charged with Ann’s murder following a cold case review of the original evidence and remanded in custody for a short period.

However, three months later he had all charges against him dropped because of a concrete alibi – he had been at work at GE Stiller’s, the transport depot near his home, at the time of the murder.

Despite several TV appeals on BBC’s Crimewatch programme and other cold case reviews Ann’s killer has never been caught.

The Durham Police investigation to date has spanned an estimated 100,000 hours and saw around 7000 people being interviewed and 4000 statements taken.

In a newspaper interview in July 2020, Peter, now aged 85, described the horrific scene he found the day he came home from work which he said was ‘forever etched’ on his memory.

Glasgow Times: Peter HeronPeter Heron (Image: Newsquest)

He recalled: “The first thing I noticed when I drove up the drive that day was the door was open and the dog was outside.

“Ann was going out that night with friends and she had pleaded with me to come home at a reasonable time.

“I walked into the hall and shouted her name, there was nothing.

“I then opened the door of the lounge and found her. I went straight to the phone and called the police, and they were there within 10 to 15 minutes. That was the beginning of the horror.”

Peter, who has always protested his innocence, remains one of only two people to fall under the finger of suspicion.

`The other is former army chef Michael Benson, a travelling criminal with a history of violence and knife crime and who was on the run from prison at the time of Ann’s murder.

He was identified as a subject by criminologist Jen Jarvie, a former head of undergraduate policing at Sunderland College, whose specialities include cold cases and missing persons.

Jen discovered that Benson had bases in his hometown of Leeds – a 45-minute drive from Darlington – and Southampton.

Furthermore, he had convictions for firearms offences, burglary and robbery with a carving knife.

He was given a life sentence in December 1972 for grievous bodily harm.

In May 1989 he absconded from prison while on a day-release programme and remained under the radar of the authorities until his death in 2011.

During his time on the run, he married but left his wife in June 1990, taking her blue Ford Orion car – similar to the car spotted leaving the murder scene.

Jen, who is convinced of Peter’s innocence, believes Benson is the mystery man who sent letters in 1994, claiming to be the killer.

One letter also made a reference to Parkgate, an area of Southampton where Benson had lived with his wife.

Ms Jarvie said: ‘There was a lack of open-mindedness to consider anyone else other than her husband.

“Police were working on a basis popular at the time that the victim, statistically speaking, would have known her killer.

“But I can categorically say that it wasn’t Peter. All the evidence points to him being elsewhere at the time of the murder.”

Jen passed her file on Benson to police in October 2018 and DNA samples from Benson’s family were later taken in the hope they would match evidence collected from the crime scene.

However no direct link was made with Benson and following a lengthy investigation he was dismissed as a suspect.

Ann is survived by her two children Ann Marie Cockburn and Ralph Cockburn and five grandchildren.

Her third child Michael died in 2012 at the age of 37.

Ann Marie, a medical receptionist, lives in Wemyss Bay, Renfrewshire, and has two grown-up sons.

Glasgow Times: The last photo of Ann HeronThe last photo of Ann Heron (Image: Newsquest)

She last saw her mother two weeks before the murder when she came to visit with Peter and they went for lunch in Largs on the Ayrshire coast.

Ann Marie had lived with the couple for several years from the age of 17 before returning to Scotland.

In the same 2020 interview, she said: “It’s very difficult to comprehend why someone would kill my mother, who was such a loving and caring woman.

“The trail has gone cold and will probably only be solved now if someone comes forward with new evidence.”

At the time of her murder Ralph was a Detective Constable with Strathclyde Police in Glasgow.

The father-of-three had to quit on the grounds of ill health in 1996 due in part to the trauma of his mother’s murder and is now a successful insurance claims investigator in Melton Mowbray, Leicestershire.

Ralph, now 59, told the Glasgow Times this week that he is in regular contact with Durham Constabulary over his mother’s murder.

He added: “The family have an open mind as to who might be responsible and are forever hopeful that someone, one day, will be finally brought to justice.”

Durham Constabulary confirmed that its probe into Benson had determined that he was “not a suspect”.

A spokesperson added: “The murder of Ann Heron has been thoroughly investigated and subject to constant review over the last 33 years, including the use of new investigative techniques with the advancement of forensic technology.

 “It is still the ambition of Durham Constabulary to convict the person responsible for Ann’s murder. 

 “At this time there is no new evidence that identifies new suspects, but we remain open-minded and committed.”